The present embodiments relate to acoustic radiation force impulse (ARFI) imaging. For example, by transmitting an ARFI excitation pulse, ultrasound may be used to displace tissue directly or through generation of a shear or longitudinal wave. The displacement resulting from the wave generated by the excitation pulse may be measured using further ultrasound scanning or tracking.
To determine the velocity of the generated shear wave in tissue, displacements are estimated over time for each location. The maximum displacement over time and/or the relative phase shift in displacement temporal profiles between locations is found. The number of locations that can be tracked simultaneously depends on the maximum number of simultaneous receive beams provided by the system beamformer. To increase the size of the tracking area, more simultaneous receive beams are required (e.g., a costly, newer system is used) or repeated ARFI pushes are used to sample other tracking locations.
Excitation pulses are repeated to measure displacement at different laterally spaced locations. Depending on the size of the tracking area and the number of simultaneous receive beams used in tracking, many ARFI push transmissions may be required. However, the repetition of ARFI pulses may cause undesired transducer heating and introduce delays in scanning.